Process for treating yeast



Patented May 16, 1933 UNITED STATES PATENT OFFICE HENRY RILEY, OF KEARNY, NEW JERSEY PROCESS FOR TREATING YEAST No Drawing. k Application filed April 27, 1929. Serial NO. 358,754.

This invention relates to yeast and more It isan object of the invention to provide particularly to a process for increasing the a process for building up zymase in yeast, zymase in yeast and the production of a powfixing it, drying the yeast and adding cerdered zymase which has great fermenting tain materials to act as stimulants to assist property. the fermentation. 7

It has been found convenient to supply A further object is the provision of a procyeast in a powdered form or dried for bakers ess for building up the zymase content of and other users but yeast in such forms is yeast. of slight value inasmuch as its essential A further object of this invention is to 10 properties have been destroyed during the provide a process for increasing the zymase process of manufacture. In yeast, zymase in use, at the same time suppressing the, acis the most beneficial constituent and the tion of the destructive endotryptase so that endotryptase and lipase are constituents of the final product may be subject to drying yeast which tend to destroy the zyniase untemperatures and still retain all of its beneder certain conditons. These destructive ficial properties present at the low tempera- 65 elements are ineffective at low temperatures, tures. but when the temperature of the yeast is A further object of the invention is to raised, as is necessary in the drying process, provide a method greatly increasing the zythe endotryptase and lipase become very mase content of yeast in the raw condition.

powerful and readily destroy the beneficial A further object is the production of a 70 zymase content. powdered zymase which may be effectively The available zymase eff ct appear to mixed with ordinary soft yeast in order to depend primarily upon the permeability of increase the zymase content of the latter. the yeast cells and it is known that increas- In carrying out the invention, yeast taken ing the permeability of the cell walls allows from a fermen ation rich in zymase is kept 75 a greater fermenting action. But Whether at a low temperature so that the zymase conthis is due to the inclusion of the enzyme in tent will not be affected by the endotryptase the presence of its substrate into the cell nd lipase pres nt in he yeast. The yeast, is r not known definitely. Howev r, .it is which is already rich in zymase is then subknown that in yeast cells there exists an jected to the action of a lipase inhibitor in so enzyme called endotryptase, which is also S9011 m nt an t Su h a time as to efi'ecpresent in yeast juice. Under ordinary contlvely s ppress the endotryptase actively ditions this endotryptase attacks and depresent in the yeast, as the zymase is a destroys the zymase sirable enzyme in fermentation, and the en- Ordinary dried yeast on the market is so dotryptase is not desirable in the fermentacarefully dried and preserved that the proctiOn f d0ughess does not take into account the fact that I have found that Steffens waste water in fermentation yeast hardly grows or multia waste product obtained during the conm plies when it is deprived of its oxygen, and version of molasses into sugar is an eflt'ective all known drying processes favor the de agent for the suppression of the endotrypstructive endotryptase and lipase at the xtase activity of yeast. Instead of using Stefl pense of the zymase. Manufacturers of dry fens waste water, excellent results may be yeast all st'rive to keep the yeast cells alive, Obtained by the use of boiled yeast juice. not taking into account the fact that yeast By he use of thisjvaste Water a considerresists drying. These processes require exable saving is obtained from the known way 9 pensive equipment, and I the temperature of increasing the zymase activity, that is, by used in drying the yeast cell favors the endousing expensive stearic acid as described in try tase which destroys the zymase thus Patent No. 1,651,027, February 29, 1927. ma ing dried yeast a poor substitute for the The Stefi'ens waste water is rich in bios mo well known commercial compressed yeast. and it is no doubt due to these elements that it is a powerful agent for increasing zymase activity.

As an example: To one pound of yeast is added one ounce of Stefiens waste Water, one gallon of water, one ounce of sugar, and this mixture is allowed to stand for twelve hours, it being stirred about every two hours. At the end of the standing period the product may be compressed in the usual manner, into cakes. It should be understood that I may use other products rich in bios as for instance, boiled yeast juice, which aims to protect the zymase for a period of time against the proteolytic action of the endotryptase. Yeast produced in this manner will give quicker fermentation in the baking process, as it is rich in the beneficial zymase and the endotryptase activity has been eifectually suppressed.

In the above process instead of using sugar, other substances such as maltose, dextrose, and sugary bodies of the levulose and glucose class may be used.

Heretofore there has been known a method of fixing zymase in the yeast cell by acetone or alcohol. Heretofore no one has disclosed a method of increasing the zymase at the same time suppressing the endotryptase, and then fixing the zymase so that it may be used in place of commercial dried yeast.

It will then be seen that my process consists essentially in the building up of the zymase by the use of Steifens waste water or yeast juice, washing the yeast and then fixing the zymase with acetone, after which it is dried at about 45 degrees F. to obtain a white powder rich in zymase. A similar powder may be obtained by precipitating Buchners yeast nice with alcohol. This yeast juice or white powder may be added to commercial dried yeast or to commercial yeast before it is compressed to build up the zymase content without resorting to special treatment.

It is a well known fact that commercial dried yeast is about 90% dead and to such a yeast a quantity of my zymase powder may be added to revivify the dry yeast and bring it back to its original strength. Also the zymase powder or yeast juice may be used directly for baking purposes without previously combining it with dried or com pressed yeast.

After the zymase has bee'n-builtup in accordance with my process, fixed with acetone, and dried, it is desirable that certain mineral salts such as potassium phosphate or sodium sulphate be added, as these salts act as stimulants and assist the fermenting action of. the zymase. In the example given above, one gram of potassium phosphate and 0.1 per cent of sodium sulphate would be added. Instead of adding the mineral salt I may add certain preservative substances such as a heavy concentration of maltose,

dextrose, protein materials derived from cereals, sugary bodies of the levulose and glucose class. The addition of such preservatives prevents further action of any endotryptase which may remain in the yeast.

From the above description it will be seen that I have presented a practicable method of fixing the zymase'content of yeast. The zymase may be fixed by acetone, alcohol or ether, and it is preferable that the zymase be built up before it is fixed.

Heretofore, a powdered zymase adapted to be used in placeof commercial dried yeast has not been available on the market, chiefly because no practical commercial method was known for building up the zymase and for fixing. 'The process herein disclosed enables the productionof a powdered zymase for commercial purposes which may be used in place of commercial dried yeast or added to compressed yeast for building up the zymase content.

Having thus described my invention, what I claim as new'and desire to secure by Letters Patent, is:

1. The process of making a dried yeast, comprising allowing yeast to stand in a mixture of Stefi'ens waste water and a dilute solution of sugar, intermittently stirring the mixture, adding acetone to the mixture, then drying the mixture, and then adding potassium phosphate and sodium sulphate.

2. The process of making dried yeast, comprising allowing yeast to stand in yeast juice and a dilute solution of sugar, intermittently stirring the mixture, adding acetone, and then drying the mixture.

3. The process of making a dried yeast, comprising adding to one pound of yeast one gallon of water and one ounce of sugar and one ounce of Steffens waste water, allowing the mixture to stand with intermittent stirrin for about 12 hours, adding acetone, then rying the mixture at a temperature of about 45 F.

4. The process of making a dried yeast, comprising adding to one pound of yeast one gallon of water and one ounce of sugar and one ounce of Stefl'ens waste water, allowing the mixture to stand with intermittent stirring for about 12 hours, adding acetone, then drying the mixture at-a temperature-of about 45 F., then adding one gram of potassium phosphate and 0.1 per cent of sodium sulphate.

This specification signed this 25th day of April 1929.

- HENRY RILEY.

ill 

